1. Field of the Invention
The present invention is related to a color sequential control method, and more particularly, to a color sequential control method and a field sequential color display using the method.
2. Description of Related Art
In recent years, flat panel displays are developed rapidly owing to mature photoelectric technology and semiconductor manufacturing technology. Liquid crystal displays (LCDs) advantageous in small volume, low-voltage operation, no-radiation, lightness, and lower electromagnetic interference have gradually become a mainstream produce in the market.
The LCD mainly includes a liquid crystal panel and a backlight module. As the liquid crystal injected into the liquid crystal panel does not emit light itself, the liquid crystal panel must be illuminated by a surface light source provided by the backlight module, so that the LCD can display images.
Color display mixing method of the LCD is mainly classified into two types, namely temporal color mixing and spatial color mixing, which is so-called simultaneous additive color mixing. Currently, the spatial color mixing is the commonly used color display mixing in displays. Taking thin-film transistor LCD (TFT-LCD) for example, each pixel is composed of three sub-pixels of red, green, blue (RGB) distributed on a color filter. When the sub-pixels are small beyond the distinguishable viewing angle of human eyes, a color mixing effect is observed by visual perception.
If the spatial color mixing of the TFT-LCD is replaced by the temporal color mixing, there is no need to use the color filter to achieve the color mixing effect. Instead, different color backlights are directly used in sequence with relative data to display images, so as to achieve the temporal color mixing effect and to display a color frame. Hence, the transmission rate of the module is increased and the overall manufacturing cost of the module is decreased.
FIG. 1 is an architectural diagram of a driving circuit of a conventional field sequential color display (FSCD) 1000. Referring to FIG. 1, an FSCD controller 1400 is used to convert a spatial parallel RGB video data at a system of a video source 1200 into a temporal serial R→G→B video data and then output it. Next, the FSCD controller 1400 synchronously controls a backlight module 1600 according to different primary color data to generate a corresponding light source so that a display panel 1800 displays a color frame.
In addition, in order to prevent a false color mixing when the RGB data is written during data scanning, the light source of the backlight module 1600 is turned on or off according to data scanning.
FIG. 2 is a conventional FSCD driving waveform diagram. Referring to FIG. 2, when the data is written, the light source of the backlight module 1600 is turned off. After the data is written, the light source of the backlight module 1600 is turned on, so that the temporal color mixing of the RGB is achieved and the false color mixing is prevented. Besides, since the temporal color mixing method divides a color frame into R, G and B the three primary color images and 180 Hz image updating frequency of the LCSD needs to be achieved when the R, G and B color images are displayed in sequence during a frame period. It represents that the response time of the liquid crystal needs to be at least below 5.56 ms, such that the false color mixing is prevented.
However, when human eyes move rapidly relative to the display screen due to random viewing or an instinct for tracing a moving object, the R, G, and B images of the object do not fall at the same location of the retina. This results in color breakup (CBU) or perceived spatial separation of the R, G, and B components as using the FSCD. Besides, the CBU usually forms a color band around the edge of the object, which is like a rainbow, and hence the CBU is so-called rainbow effect.
The CBU not only reduces the image quality, but also makes observers feel dizzy after a long time onlooking which is pointed out by some reports. Present methods of reducing the CBU mainly performs by increasing the response rate of liquid crystal, by changing the sequence of color fields, or by using dynamic picture compensation . . . and so on. However the above methods are unable to eliminate the CBU effectively throughout, and all need complex control algorithm as well as formidable driving circuit ability so that the mass production of the FSCD is limited.